Three-dimensional force analyses of an axial-flow radial-flux permanent magnet motor with magnetic suspension

This paper will provide a thorough evaluation of a specially designed axial-flow radial-flux permanent magnet motor for cooling fan applications. With a passive magnetic suspension segment implemented, the design objective of this motor is to provide a stable guidance force in its axial direction, such that the vibration effects at the entire rotor operational positions can be minimized and the net radial forces applied onto associated bearing system can be alleviated. Supported by dynamic magnetic circuit modeling and static/quasi-dynamic three-dimensional finite element analyses, the operational forces of such motor, either with or without magnetic suspension, at its respective radial, axial, and tangential directions will all be evaluated. Results show that the motor, which being implemented with a low-cost passive magnetic suspension segment, can supply excellent operational characteristics and thus enhance the operational reliability.